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A rotational excitation spectrum of SO2 [^-A^1A2(511)←^-X^1A1(000)] at about 33331cm^-1 in free jets was observed by using the forward degenerate four-wave mixing (DFWM).Twelve lines of the G band and 11 ones of the E band were marked based on the rotational constants according to Hamada‘s result [Can.J.Phys.53(1975)2555].The relation between the DFWM signal intensity and the pressure of the buffer gas in free-jets was experimentally investigated. 相似文献
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Transient Hole Trapping in Individual GeSi Quantum Dot Grown on Si(001) Studied by Conductive Atomic Force Microscopy 下载免费PDF全文
Electrical properties of individual self-assembled GeSi quantum dots grown on Si substrates are investigated by using conductive atomic force microscopy at room temperature. By controlling the bias voltage sweep in a certain fast sweep rate range, a novel current peak is observed in the current-voltage characteristics of the quantum dots. The current peaks are detectable only during the backward voltage sweep immediately after a forward sweep. The current peak position and intensity are found to depend strongly on the voltage sweep conditions. This kind of current-voltage characteristic under fast sweep is very different from the ordinary steady state current behaviour of quantum dots measured previously. trapping in the potential well formed bottom Si substrate. The origin of this phenomenon by the quantum dot sandwiched can be attributed to the transient hole between the native oxide layer and the 相似文献
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Nanodot arrays were formed on Si(110) surface under normal-incident Ar ion sputtering at substrate temperature of 800℃ The ion flux was 20μA/cm^2, and the ion energies were 1-5keV. The surface was imaged by an atomic force microscope (AFM). It was found that with the increasing ion energy, the average e11ipticity of the dots changes in an oscillating manner; meanwhile the average dot size increases monotonously. Based on a dynamic continuum model, and taking into consideration the asymmetry of the Ehrlich-Schwoebel diffusions along the(100) and (110) crystallographic directions, we carry out the simulations, which reproduce the experimental results qualitatively. 相似文献
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本文研究了离子能量为1.5keV、束流密度为20?A/cm2正入射Ar+离子束溅射致Si(110)表面形貌随样品温度变化的演化过程。在温度自室温上升至 800?C的过程中, Si(110) 的表面形貌由不规则的纳米点和纳米孔图案变为密集的量子点阵列,同时表面粗糙度也随温度上升不断增加。被通常采用的 Bradley-Harper 模型无法解释上述实验数据。 在考虑溅射过程中存在Ehrlich-Schwoebel 效应后, 进行了已连续动态模型为基础的理论模拟,模拟工作很好的重复了实验结果。 相似文献
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We investigate Si(100) surface morphology evolution under normal-incident Ar^ ions sputtering with low ion flux of 20μA/cm^2. The results indicate that under the low flux ion sputtering, the nanostructuring process of Si(lO0) is governed by the Ehrlich-Schwoebel (ES) mechanism, rather than by the Bradley-Harper (1311) one for the case of high flux (normally the order of 10^2 μA/cm^2 or larger). This work reveals that the ion flux plays an important role in the surface morphology evolution under ion sputtering, and a usually accepted classification that the ES mechanism is related to metal single-crystals under ion sputtering, while the BH one is to amorphous,and semiconductor targets is questionable. 相似文献
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应用一手数据研究了上海入境外国旅游流的分布和扩散规律及网络结构特征,发现:(1)上海口岸入境外国旅游流集中分布在胡焕庸线东南部,北京、桂林、西安、成都和昆明等城市以及长三角地区、珠三角地区构成的主体骨架,并在全国范围内呈由长三角地区向西北方向、西南方向扩散的态势;(2)上海口岸入境的韩国旅游流空间分布呈“倒皇冠”型,主要由“上海-杭州-苏州”、“上海-杭州-西安”和“上海-杭州-广州”3个三角形构成;美国旅游流空间分布呈“Z”型,由“上海-南京-杭州-桂林-北京”连接而成;美国游客比韩国游客活动范围更广,游览目的地更多,对上海口岸的依赖程度较低;(3)网络中的节点可划分为枢纽节点、中转节点、重要节点和一般节点,其中,上海、北京、桂林、西安、杭州和苏州等11个节点属于枢纽节点;(4)上海口岸入境外国旅游流网络规模较大,整体结构较松散,围绕核心节点集聚或扩散的趋势较强,具有小世界网络特性. 相似文献
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采用脉冲激光沉积技术在氧气氛中制备了Ga2O3薄膜。X射线衍射表明薄膜属于β单斜晶系,薄膜的颗粒在纳米量级;原子力显微镜显示随着氧气压强的增加,薄膜颗粒增大。测定了薄膜的光致发光,发现沉积时氧气压强的增加可以提高 纯Ga2O3薄膜的发光强度,且峰位红移。Ga2O3靶物质中掺杂少量的CeO2后所得到的薄膜,其发光强度可以明显地增加。此外,还利用发光光谱技术研究了由激光 烧蚀所产生的羽状物中Ga原子或离子的氧化反应。 相似文献